DVB‐S2 modem algorithms design and performance over typical satellite channels

Abstract

SUMMARYIn this paper we propose a design of the main modulation and demodulation units of a modem compliant with the new DVB-S2 standard (Int. J. Satellite Commun. 2004; 22:249-268). A typical satellite channel model consistent with the targeted applications of the aforementioned standard is assumed. In particular, non-linear pre-compensation as well as synchronization techniques are described in detail and their performance assessed by means of analysis and computer simulations. The proposed algorithms are shown to provide a good trade-off between complexity and performance and they apply to both the broadcast and the unicast profiles, the latter allowing the exploitation of adaptive coding and modulation (ACM) (Proceedings of the 20th AIAA Satellite Communication Systems Conference, Montreal, AIAA-paper 2002-1863, May 2002. Finally, end-to-end system performances in term of BER versus the signal-to-noise ratio are shown as a result of extensive computer simulations. The whole communication chain is modelled in these simulations, including the BCH and LDPC coder, the modulator with the pre-distortion techniques, the satellite transponder model with its typical impairments, the downlink chain inclusive of the RF-front-end phase noise, the demodulator with the synchronization sub-system units and finally the LDPC and BCH decoders.

Generalized direct predistortion with adaptive crest factor reduction control

“…As transpon der model, we consider an input multiplexer filter (IMUX), a HPA, and an output multiplexer filter (OMUX). Typical responses for the IMUX and OMUX filter are extracted from [25] and modelled as FIR filters. On the other hand, the HPA is parameterized using the standard Saleh model with AM/AM and AMIPM functions taking the form A(r) = 1 ��2; <I>(r) = % 1 ::2, respectively [16].…”

Iterative Predistortion of the Nonlinear Satellite Channel

“…The performance of pre-distortion or equalization algorithms in a non-linear satellite channel is usually quantified in terms of the total degradation [19], [20], [22]. The total degradation, denoted as TD, is defined as follows: (2), the total degradation depends on the OBO, and the optimum OBO which minimizes the total degradation can significantly be different depending on the considered pre-distortion technique, as shown in [19], [20], [22].…”

“…The total degradation, denoted as TD, is defined as follows: (2), the total degradation depends on the OBO, and the optimum OBO which minimizes the total degradation can significantly be different depending on the considered pre-distortion technique, as shown in [19], [20], [22]. Pre-distortion techniques must therefore be compared based on the minimum total degradation they can reach.…”

“…The pre-computation of these values aims at minimizing the MSE between the initial and the received symbols. The performance of this algorithm has been assessed for high-order modulations in [20].…”

Architecture and DSP Implementation of a DVB-S2 Baseband Demodulator

“…Phase compensation is based on the interpolation between the estimations of two consecutive pilot fields. When high-order modulations of 16APSK or 32APSK are used, an additional phase synchronizer is needed, which consists of a closed-loop based on the NDA phase error detector of Q-th power (Q=3 for 16APSK and Q=4 for 32APSK) [12]. This NDA feedback loop is located after the digital amplitude control unit, which is described in the next subsection, and is initiated as soon as the ML feed-forward coarse estimator has reached its steady state.…”